Data analyzing and/or combined main/mobile receiving

ABSTRACT

Mobile/handheld (M/H) data is received in an M/H frame equivalent in size to exactly 20 VSB data frames. Each VSB frame contains an odd VSB field and an even VSB field, and each of the VSB fields includes one field sync segment and 312 data segments. The M/H frame includes main data and M/H data, and the M/H data has more robust coding than the main data. The M/H frame is received and an MPEG encoded transport stream derived therefrom is outputted. Frame registration is found so as to find a structure of the M/H frame in the MPEG encoded transport stream. Based on the structure of the M/H frame, the M/H data is randomized. Based on the structure of the M/H frame, block mode data is located within the randomized M/H data. The M/H data is decoded using the block mode data.

RELATED APPLICATION

The present application contains disclosure similar to disclosurecontained in application (7290).

TECHNICAL FIELD

Data analyzing such as might be used to verify proper operation of atransmitter and combined main/mobile receiving such as might be used toreceive both main data and mobile data under the ATSC A/153 part 2Standard are described herein.

BACKGROUND

The ATSC transmission scheme set out in the ATSC A/53 Standard involvesthe use of 8-VSB modulation in transmitting terrestrial and cablebroadcasts for digital television receivers. An ATSC A/53 field (an ATSCA/53 frame has an odd field and an even field) contains a field syncsegment and 312 data segments each beginning with a segment sync. Thedata segments also include main data. ATSC A/53 is optimized for fixedreception.

Unfortunately, transmissions according to this standard are not robustenough against doppler shift and multipath radio interference in mobileenvironments because it is designed for slowly varying signalconditions. In order to provide robust reception in spite of dopplershifts and multipath radio interference in mobile environments,additional channel coding mechanisms are introduced in the ATSC a/153Standard to protect the signal.

The A/153 Standard describes the ATSC Mobile DTV system referred to inthe Standard as the ATSC mobile/handheld (M/H) system. The M/H systemprovides mobile/pedestrian/handheld broadcasting services using aportion of the ATSC 8-VSB payload, while the remainder is stillavailable for HD and/or multiple SD television services. The M/H systemis a dual-stream system that includes the ATSC service multiplex forexisting digital television services and the M/H service multiplex forone or more mobile, pedestrian and handheld services.

Thus, the ATSC A/153 Standard known as ATSC-M/H is a standard for mobiledigital televisions that allows television broadcasts to be received bymobile devices. ATSC-M/H is an extension to the available digital TVbroadcasting standard ATSC A/53.

According to Part 2 of the A/153 Standard, one M/H Frame can carry maindata (processed in accordance with the A/53 Standard) and M/H data(processed in accordance with the A/153 Standard) and is equivalent insize to exactly 20 VSB data frames. The M/H Frame consists of fiveconsecutive Sub-Frames such that each Sub-Frame contains the same amountof data as four VSB data frames or eight A/53 data fields. EachSub-Frame consists of sixteen consecutive M/H Slots. Each M/H Slotconsists of 156 transport stream packets or equivalently 156 datasegments at the symbol level, i.e., equivalent to one half of a A/53data field. A particular Slot may contain M/H data, a combination of M/Hdata and main data, or only main data. If an M/H Group is transmittedduring an M/H Slot, then the first 118 transport stream packets in theSlot belong to an M/H Group, and the remaining 38 packets are main datapackets. If there is no M/H Group in an M/H Slot, the M/H Slot contain156 main data packets. As in the case of an A/53 field, an A/153 fieldhas a field sync segment and each data segment includes a segment syncportion.

There is no method to verify that all of the M/H data is properly placedin the frame. Current receivers output decoded data or decoded FIC (FastInformation Channel) data. TPC (Transmission Parameter Channel) data isavailable on a sub-sampled register basis. However, it is not presentlypossible to verify training signals, M/H RS (Reed Solomon) data, CRC(Cyclic Redundancy Check) data, and/or M/H TP (Transport Packet) headerdata. Similarly, it has not been possible to check every instance of TPCdata or the proper placement and values of FIC data. For debugging, itis important to have the raw data stream to verify the robust coders andproper parameter signaling.

Thus, there has been confusion among transmitter manufacturers as theytry to create M/H modulators.

Accordingly, it is desirable to have available a data analyzer thatverifies training signals, M/H RS (Reed Solomon) data, CRC (CyclicRedundancy Check) data, and/or M/H TP header data as well as everyinstance of TPC data and/or the proper placement and values of FIC datain M/H transmitters.

Moreover, the only option for both main and mobile reception has beenthe use of two separate receivers, one for main data and one for M/Hdata.

The ATSC Mobile/Handheld service (M/H) shares the same RF channel as astandard ATSC broadcast service described in ATSC A/53, also known asthe “Main service.” Hence, main data is data ordinarily transmitted inaccordance with the ATSC A/53 standard. M/H data is data that receivesextra coding to give the data more robustness than main data. This extracoding conforms to the ATSC A/153 Standard.

Accordingly, it is desirable to have available a single receiver thatreceivers both main and mobile data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a data analyzer that is capable ofanalyzing M/H data; and,

FIG. 2 is a block diagram of a combined Main and Mobile receiver.

DETAILED DESCRIPTION

As shown in FIG. 1, a data analyzer 10 has a receiver 12 that receivesand demodulates the VSB television signal supplied by a VSB transmitter.The receiver 12, for example, may be a receiver manufactured accordingto the ATSC Digital Televisions Standard A/53. As such, the output ofthe receiver 12 is an MPEG transport stream.

The MPEG transport stream from the receiver 12 is provided to aprocessor 14 such as a post-processor. The processor 14 includes a frameregistration find block 16, a randomization block 18, a trainingsequence, FIC, and TPC block 20, an M/H decode block 22, and a dataselect block 24. The processor 14, for example, may be one or moreelements of a computer. The computer for example, may include memory,one or more input devices such as a mouse and/or a keyboard, one or moreoutput devices such as a display and/or a printer, one or moreprocessing elements such as a microprocessor, etc. In this case, theblocks of the processor 14, for example, may be blocks of code executedby the processor 14. Alternatively, each of the blocks of the processor14 or various combinations of the blocks of the processor 14 may behardware and/or firmware such as ASICs or other ICs.

The frame registration find block 16 finds the frame registration (i.e.,location or structure of the frame) in the MPEG transport streamprovided by the receiver 12. Finding frame registration enables theprocessor 14 to find the location of the mobile data whose value andposition in the transport stream frames is to be verified to ensureproper operation of the transmitter. The frame registration find block16 may find the frame registration in a number of ways.

For example, the frame registration find block 16 may locate thetraining sequence in the MPEG transport stream provided by the receiver12. The location of the training sequence in the MPEG transport streamprovided by the receiver 12 is predetermined even though the MPEGtransport stream provided by the receiver 12 is deinterleaved by thereceiver 12. Because the training sequence has a predetermined locationin the frame, the frame structure within the MPEG transport streamprovided by the receiver 12 is easily determined.

Alternatively, if the receiver 12 is configured to provide an outputcorresponding to the frame sync of a frame, the frame registration findblock 16 can use the frame sync to easily find the frame structurewithin the MPEG transport stream provided by the receiver 12.

As another alternative, the frame registration find block 16 can findthe PID that identifies the packets containing mobile data. Because themobile data has predetermined locations within the frame, the frameregistration find block 16 can use the mobile PID to easily locate theframe structure within the MPEG transport stream provided by thereceiver 12.

Once the frame structure is located within the MPEG transport streamprovided by the receiver 12, the M/H data in the located frame structureis randomized by the randomization block 18. The receiver 12, as one itsfinal processing steps, derandomizes the transport stream. However, thetransmitter does not randomize the mobile (M/H) data that it transmits.Therefore, the mobile data in the transport stream provided by thereceiver 12 is not correctly represented. Accordingly, the randomizationblock 18 reverses the derandomization of the mobile data performed bythe receiver 12 and returns the mobile data to its correctrepresentation. The randomization block 18 is a byte scrambler. At thispoint, the processor 14 now knows where some of the MH data is, althoughthe value of this data is not known.

Because the location of the frame structure is determined by the frameregistration find block 16 and because the mobile data is returned toits correct representation by the randomization block 18, the trainingsequence, FIC, and TPC block 20 is able to locate and strip the trainingsequence, the FIC data, and the TPC data from the transport stream. TheFIC data essentially indicates the service locations in the MH Frame,and the TPC data provides a map that indicates where the main and mobiledata are packed into the frame. The TPC data also indicates the SCCC(Series Concatenated Convolutional Code) block mode. The trainingsequence is useful in training the equalizer of a receiver.

The TPC basically indicates to the processor 14 where the M/H data isand how to decode it. The FIC indicates to the processor 14 where theprograms are in the mobile parades and may repeat several times perframe. However, because neither the TPC nor the FIC is actual programdata, they are not included in any output stream.)

One M/H Block of data can constitute a single SCCC Block or two M/HBlocks of data can constitute a single SCCC Block. The SCCC Block Modeidentifies the relationship between the M/H Block and the SCCC block. Ifthe SCCC Block Mode is equal to ‘00’ (separate), then each SCCC Blockconsists of a single M/H Block. If the SCCC Block Mode is ‘01’ (paired),then two M/H Blocks constitute a single SCCC Block.

The M/H decode block 22 uses the SCCC block mode to determine therelationship between the M/H blocks and the SCCC blocks in order todecode the M/H data using the SCCC. The M/H decode block 22 may also bearranged to perform the functions specified in A/153 part 2, section5.3.2 to 5.3.2.6. The data select block 24 selects the M/H payload to beverified.

The M/H data to be verified generally includes the TPC data, the FICdata, the RS (Reed Solomon) Blocks, and/or the training sequence.Current receive chips output decoded data and decoded FIC data. TPC datais available on a sub-sampled basis. However, it has not been possibleto verify the training sequence, M/H RS data, CRC data, and M/H TPheader data. Similarly, it has not been possible to verify everyinstance of TPC data or the proper value and placement of FIC data. Fordebugging purposes, it is important to have available the raw datastream so that the robust coders and parameter signaling of thetransmitter can be verified. The data select block 24 outputs this rawdata stream so that the robust coders and parameter signaling of thetransmitter can be verified.

Thus, the data select block 24 selects all of the data in the raw datastream provided by the M/H decode block 22. Alternatively, the dataselect block 24 can select a sub-set of the data available in the rawdata stream provided by the M/H decode block 22. For example, it may notbe desired to verify the Reed Solomon and CRC data. If this is the case,the data select block 24 need not select this data. Also, the M/H decodeblock need not decode the non-selected data.

An analyzer 26 analyzes the selected data provided by the data selectblock 24 to determine if the selected data has been properly placed inthe frame.

As shown in FIG. 2, a combined main/mobile receiver 30 is arranged toreceive both main data (data that has not received the robust extracoding that the mobile data receives) and mobile data (data that hasreceived the robust extra coding). Previously, separate main and mobilereceivers were necessary to receive both main and mobile data.

The combined main/mobile receiver 30, for example, includes the samereceiver and processor as in FIG. 1 and, hence, the same referencenumerals are used to designate common elements. Accordingly, thecombined main/mobile receiver 30 includes the receiver 12 and theprocessor 14 of FIG. 1. Also, the processor 14 includes the frameregistration find block 16, the randomization block 18, the trainingsequence, FIC, and TPC block 20, the M/H decode block 22, and a dataselect block 24.

For main reception, the MPEG-2 transport packet output of the receiver12 is provided to an MPEG-2 decoder 32 that uses the decoding specifiedin the ATSC A/53 Standard to decode the main data and that provides theMPEG-2 decoded data to a television monitor 34. Packets not relevant tothe chosen program (such as mobile data) are ignored. For M/H reception,the data select block 24 selects and provides the M/H data to an MPEG-4decoder 36 that uses the decoding specified in the ATSC A/153 Standardto decode the M/H data and that provides the MPEG-4 decoded data to thetelevision monitor 34. In this way, the user of the television monitor34 has the option of displaying main data or M/H data on the sametelevision monitor and does not need separate receivers to be able toreceive both main and M/H data.

(Both the mobile receiver and the main receiver have a CPU to processthe table data (PSIP) to determine what data in the stream is relevantto the current program. The stream entering the MPEG-2 decoder is notscrambled or coded, it is the MPEG-2 transport stream.)

Certain modifications of the present invention have been discussedabove. Other modifications of the present invention will occur to thosepracticing in the art of the present invention.

Accordingly, the description of the present invention is to be construedas illustrative only and is for the purpose of teaching those skilled inthe art the best mode of carrying out the invention. The details may bevaried substantially without departing from the spirit of the invention,and the exclusive use of all modifications which are within the scope ofthe appended claims is reserved.

What is claimed is:
 1. A method of processing mobile/handheld (M/H) datareceived by a receiver in an M/H frame equivalent in size to 20 VSB dataframes, wherein each VSB frame contains an odd VSB field and an even VSBfield, wherein each of the VSB fields includes one field sync segmentand 312 data segments, wherein the M/H frame includes randomized maindata and non-randomized M/H data, and wherein the non-randomized M/Hdata has more robust coding than the randomized main data, the methodcomprising: receiving a transmitted M/H frame by a receiver andoutputting on a first path an MPEG encoded transport stream comprising acorrect representation of the main data and outputting on a second pathan incorrect representation of the M/H data, wherein the second path isseparate from the first path; in the second path, finding frameregistration so as to find a structure of the M/H frame in the MPEGencoded transport stream; in the second path, based on the structure ofthe M/H frame, correcting the representation of the M/H data; in thesecond path, based on the structure of the M/H frame, locating blockmode data within the correctly represented M/H data; and in the secondpath, decoding the correctly represented M/H data using the block modedata.
 2. The method of claim 1, wherein the locating of block mode datawithin the correctly represented M/H frame comprises locating a trainingsequence, fast information channel data, and transmission parameterchannel data within the correctly represented M/H frame, wherein thefast information channel data indicates service locations in thecorrectly represented M/H Frame, and wherein the transmission parameterchannel data indicates where the main and mobile data are packed intothe correctly represented M/H frame.
 3. The method of claim 1, furthercomprising: selecting portions of an M/H payload from the decodedcorrectly represented M/H data; and verifying proper value and placementof the selected portions in the correctly represented M/H frame.
 4. Themethod of claim 3, wherein the locating of block mode data within thecorrectly represented M/H frame comprises locating a training sequence,fast information channel data, and transmission parameter channel datawithin the correctly represented M/H frame, wherein the fast informationchannel data indicates service locations in the correctly represented MHFrame, and wherein the transmission parameter channel data indicateswhere the main and mobile data are packed into the correctly representedM/H frame.
 5. The method of claim 1, further comprising: MPEG-2 decodingthe MPEG encoded transport stream to produce MPEG-2 decoded data;selecting portions of an M/H payload from the decoded correctlyrepresented M/H data; MPEG-4 decoding the selected portions to produceMPEG-4 decoded data; and providing the MPEG-2 decoded data and theMPEG-4 decoded data to a data operator that operates on the data.
 6. Themethod of claim 5, wherein the locating of block mode data within thecorrectly represented M/H frame comprises locating a training sequence,fast information channel data, and transmission parameter channel datawithin the correctly represented M/H frame, wherein the fast informationchannel data indicates program IDs, and wherein the transmissionparameter channel data indicates where the main and mobile data arepacked into the correctly represented M/H frame.
 7. The method of claim5, wherein the data operator comprises a television.
 8. A system thatprocesses transmitted mobile/handheld (M/H) data received in an M/Hframe equivalent in size to 20 VSB data frames, wherein each VSB framecontains an odd VSB field and an even VSB field, wherein each of the VSBfields includes one field sync segment and 312 data segments, whereinthe M/H frame includes randomized main data and non-randomized M/H data,and wherein the non-randomized M/H data has more robust coding than therandomized main data, the system comprising: a receiver that receivesthe transmitted M/H frame and outputs on a first path an MPEG encodedtransport stream comprising a correct representation of the main dataand outputs on a second path an incorrect representation of the M/Hdata, wherein the second path is separate from the first path; in thesecond path, a frame registrar that finds a structure of the M/H framein the MPEG encoded transport stream; in the second path, a randomizerthat corrects the representation of the M/H data based on the structureof the M/H frame; in the second path, a block mode data finder thatlocates block mode data within the correctly represented M/H data basedon the structure of the M/H frame; and in the second path, a decoderthat decodes the correctly represented M/H data using the block modedata.
 9. The system of claim 8, wherein the block mode data finder isarranged to locate a training sequence, fast information channel data,and transmission parameter channel data within the correctly representedM/H frame, wherein the fast information channel data indicates servicelocations in the correctly represented MH Frame, and wherein thetransmission parameter channel data indicates where the main and mobiledata are packed into the correctly represented M/H frame.
 10. The systemof claim 8, further comprising: a data selector that selects portions ofan M/H payload from the decoded correctly represented M/H data; and adata verifier that verifies proper value and placement of the selectedportions in the M/H frame.
 11. The system of claim 10, wherein the blockmode data finder is arranged to locate a training sequence, fastinformation channel data, and transmission parameter channel data withinthe correctly represented M/H frame, wherein the fast informationchannel data indicates service locations in the correctly represented MHFrame, and wherein the transmission parameter channel data indicateswhere the main and mobile data are packed into the correctly representedM/H frame.
 12. The system of claim 8, further comprising: an MPEG-2decoder that MPEG-2 decodes the MPEG encoded transport stream to produceMPEG-2 decoded data; a data selector that selects portions of an M/Hpayload from the decoded correctly represented M/H data; an MPEG-4decoder that MPEG-4 decodes the selected portions to produce MPEG-4decoded data; and a data operator that operates on the data provided bythe MPEG-2 decoded data and the MPEG-4 decoded data.
 13. The system ofclaim 12, wherein the block mode data finder is arranged to locate atraining sequence, fast information channel data, and transmissionparameter channel data within the M/H frame, wherein the fastinformation channel data indicates service locations in the MH Frame,and wherein the transmission parameter channel data indicates where themain and mobile data are packed into the M/H frame.
 14. The system ofclaim 12, wherein the data operator comprises a television.
 15. A methodas claimed in claim 1, wherein said step of receiving receives bothrobust data and main data, and further comprising: outputting a maintransport stream from the receiver; decoding the main transport streamin the first signal path to obtain the main data for use in a dataoperator; and performing the steps of finding, randomizing, locating anddecoding on the main transport stream in the second signal path toobtain the robust data.
 16. A system as claimed in claim 8, wherein thedecoder is a first decoder to decode correctly represented M/H data, andfurther comprising: a second decoder connected to an output of thereceiver.